This study compared the clinical and serologic features in two different ethnic groups of patients with childhood-onset systemic lupus erythematosus (SLE). One hundred seventy-one SLE patients comprised the study population; 61 (55 girls and 6 boys) were African American with age at onset of 13 +/- 2.9 years, and 110 (97 girls and 13 boys) were Latin American (Colombian) with age at onset of 13 +/- 3.2 years. Clinical, demographic, and laboratory data were obtained by chart review using a standard data collection form. African-American patients more commonly manifested discoid skin lesions, malar rash, pulmonary fibrosis, and pleuritis, and less commonly manifested photosensitivity, livedo reticularis, and vascular thrombosis than did Latin Americans. In addition, there was a higher frequency of anti-dsDNA, anti-Sm, anti-RNP, and anti-Ro positivity among African-Americans compared with Latin-American patients. These results suggest the presence of ethnic differences in the clinical expression of SLE.